Some Aerodynamic Aspects of Centrifugal Fan Characteristics of an Automotive HVAC Blower

Experimental and numerical approaches were adopted to understand flow behavior and performance of centrifugal fans in an automotive HVAC blower system. This work is directed at improving the performance of a conventional forward-curved centrifugal fan for a given small scroll casing. Recent requirements in the design of the multiblade centrifugal fan being used in automotive HVAC blowers are not only higher pressure rise and lower noise, but also better packaging in the automobile cabin. In order to meet these requirements, among various well-known design factors affecting the fan performance, principal parameters related to the rotor shape were modified and detailed flow analysis was carried out. Measurements have been made by means of a miniature five-hole probe and a pressure scanning system connected to an online data acquisition system. Computational results gave reasonably good predictions at the best efficiency operating point and verified the reliability of the present numerical approach. Based on the inspection of both measured and predicted results of the conventional fan, design improvements were carried out in an acceptable operation range, giving considerable insight into what features of flow behavior were most important.